Yeah, 1440x900 is the native resolution of the 15" MBP. I don't actually own a unibody MBP, so I can't be certain, but I would say yes, you are getting those results because it is in better battery life, and thus is using the 9400M card instead of the 9600M, which uses more power. The 15" MBP will handle a resolution of 2560x1600 on an external monitor. Although I don't have personal experience with it, this setup seems to be a good mobile graphics setup. The 9400M will work for many applications, and will save battery life. The 9600 will handle most heavier duty applications.